Functional Analysis Of Phytosterol Candidate Gene ZmPS7 In Maize(Zea Mays L.)

Phytosterol is a natural active substance,which is widely present in plants,plays a role in maintaining the fluidity and stability of cell membranes,and also participates in plant photosynthesis,reproduction,and immune processes.It is an essential component in plant cells.Phytosterols also play positive role in the human body.PHytosterols can reduce the risk of cardiovascular disease,have antitumor and anti-inflammatory activities,and also participate in human immune regulation and other functions.However,if the plant sterol intake is insufficient,the function of sterols cannot be revealed.The sterol content in corn oil is very considerable,so the development of high sterol content corn germplasm resources has become one of the current trends in improving genetic traits in agriculture.As of today,researches on phytosterols are mostly focused on content determination,stability,physiological function and metabolic pathway,and little is known about the key genes that regulate phytosterol accumulation.Therefore,the mining of key genes that regulate phytosterol accumulation has very important academic significance and economic value.In this study,Saccharomyces cerevisiae and Arabidopsis will be used as materials to explore the role of ZmPS7 in sterol accumulation.Meanwhile,cornwill be used as materials to explore the subcellular location of ZmPS7 in cells,and the regulatory mechanism of ZmPS7 on phytosterol accumulation will be discussed in part.The main research contents are as follows:1.Based on GWAS analysis,32 candidate genes that may be related to sterol accumulation have been preliminarily selected.In this study,we will analyze the significance of SNP markers and the correlation with sterol accumulation,further dig out a candidate gene related to sterol accumulation,and name it ZmPS7.ZmPS7 encodes a heat shock protein by bioinformatics analysis.2.By constructing a green fluorescent expression vector,the recombinant plasmid was transferred into maize protoplasts,and the green fluorescent signal was observed under a laser confocal microscope.It was determined that the ZmPS7 gene was mostly localized in lipid rafts of cell membrane,and a few were in the cytoplasm.3.The yeast overexpression vector was constructed and the transgenic yeast was obtained through genetic transformation.It was found that compared with the unloaded Saccharomyces cerevisiae,the accumulation of ergosterol increased significantly.Preliminary verification of the positive correlation between ZmPS7 and sterol accumulation.4.Plant overexpression vectors were then constructed to obtain overexpressing homozygous transformants and arabidopsis ZmPS7 homozygous mutant plants were selected at the same time.The content of phytosterols in arabidopsis overexpressed seeds is generally higher than that of wild-type and mutant seeds,but the content of phytosterols in mutant seeds is not much different than that of wild-type seeds.The content of sterols in tobacco wild-type and over-expressed seeds was determined,and it was found that the content of phytosterols in over-expressed seeds was about double that of wild-type.This indicates that the overexpression of ZmPS7 has a positive regulation effect on the accumulation of plant sterols,but the deletion of this gene has no effect on the content of plant sterols.